TOMORROW'S ROADS TODAY - Maryland State Highway ...

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of multiple members of a truss.
Resonance - The regular vibration of an object as it responds in step (at the same frequency) with an
external force.
Retractile Draw Bridge - A bridge with a superstructure designed to move horizontally either
longitudinally or diagonally from "closed" to "open" position, the portion acting in cantilever being
counterweighted by that supported on rollers; also known as traverse draw bridge.
Revet - The process of covering an embankment with stones.
Revetment - A facing of masonry or stones to protect an embankment from erosion.
Rib - Any one of the arched series of members that is parallel to the length of a bridge, especially those
on a metal arch bridge.
Rigger - An individual who erects and maintains scaffolding or other inspection access equipment.
Rigid - Ability to resist deformation when subjected to a load.
Rigidity - The measure of a structure's ability not to change shape when subjected to a load.
Rigid Frame - A structural frame in which the members are connected together without hinges.
Rigid Frame Bridge - A type of girder bridge in which the piers and deck girder are fastened to form a
single unit. Unlike typical girder bridges that are constructed so that the deck rests on bearings atop the
piers, a rigid frame bridge acts as a unit. Pier design may vary.
Rigid Frame Pier - A pier with two or more columns and a horizontal beam on top constructed
monolithically to act like a frame.
Rip Rap - Gabions, stones, blocks of concrete or other protective covering material of like nature
deposited upon river and stream beds and banks, lake, tidal or other shores to prevent erosion and
scour by water flow, wave or other movement .
Rivet - A metal fastener used in pre-1970 construction; made with a rounded preformed head at one
end and installed hot into a predrilled or punched hole; the other end was hammered into a similar
shaped head thereby clamping the adjoining parts together.
Riveted Connection - A rigid connection of metal bridge members that is assembled with rivets. Riveted
connections increase the strength of the structure.
Riveted Joint - A joint in which the assembled members are fastened by rivets.
Rocker Bearing - A bridge support that accommodates expansion and contraction of the superstructure
through a rocking action.